Setting WPA group renewal key

Hello, I'm getting disconnected on a computer that was just upgraded to
Windows XP Pro SP1. The router is a Linksys wireless-G router, WRT54G and
the PCI adapter is a Linksys Wireless-G PCI adapter WMP54G. The Microsoft
Wireless Hotfix was installed, it made no difference. On wireless networking
forums, changing the WPA Group Renewal Key to 3600...900 or 600 is
recommended. I can not find this setting in the router's setup. Has anyone
heard of this fix before, for this router. Thoughts, comments, or
suggestions are needed.
Thanks.